Now, electrophotographic arts are widely applied to copying machines and various printers owing to their high speed and high quality of picture.
Hitherto, as a photoreceptor for electrophotography in the electrophotographic arts, inorganic photoconductive materials including selenium, selenium/tellurium alloys, selenium/arsenic alloys, cadmium sulfide, etc., have been mainly used.
However, recently, from the standpoints of toxicity, safety, price, productivity, etc, photoreceptors for electrophtography used organic photoconductive materials have been developed.
When the organic photoconductive material is a low molecular substance, usually a coating film is formed by blending it with a binder resin. The binder resin for use includes various thermoplastic resins and thermosetting resins including vinyl polymers such as polymethylmethacrylate, polystyrene, polyvinyl chloride, etc., and copolymers thereof, polycarbonate, polyester, polysulfone, phenoxy resin, epoxy resin, silicone resin, etc. Among these various resins, polycarbonate resins are frequently used as the binder resin since they have comparatively excellent characteristics.
As examples using polycarbonate resins as a binder resin, for example, there are disclosed polycarbonate resin being derived from bisphenol Z in JP-A 59-71057, polycarbonate resin being derived from bisphenol A in JP-A 63-170647, polycarbonate resin being derived from dimethylbisphenol A in JP-A 63-148263, and polycarbonate resin being derived from bisphenol AP in JP-A 4-44048, which are used as a binder resin.
However, although some photoreceptors for electrophotography obtained by using these known organic photoconductive materials and various binder resins are equivalent to those used inorganic photoconductive materials in sensitivity, etc., they are still insufficient in a quality of picture, etc., and have a problem of generation of minute black spots (pin holes), etc.